如何在 C++11 中声明堆栈引用？

Question

我正在实现一个堆栈引用。但是我得到了“分段错误（核心转储）”的错误。我在 Ubuntu 14.04 上使用 g++ (Ubuntu 4.8.2-19ubuntu1) 4.8.2。非常感谢。

代码如下。

#include<iostream>
#include<stack>

using namespace std;

int main() {
    stack<int>* S;
    S->push(4);
    return 0;
}

Answer 1

尽可能停止使用new。

#include <iostream>
#include <stack>

int main() {
    std::stack<int> s;
    s.push(4);
    return 0;
}

Answer 2

通常不鼓励使用表示对象所有权的“裸”指针，因为它容易出错。要么使用自动变量，要么使用库提供的智能指针。

#include <stack>
#include <memory>

int main()
{
    // On the stack, local scope. This is the fastest;
    // unlike Java we don't have to "new" everything. 
    std::stack<int> s1;
    s1.push(4);

    // Dynamically allocated, gets auto-deleted when the
    // last copy of the smartpointer goes out of scope.
    // Has some overhead, but not much.
    // Requires some extra plumbing if used on arrays.
    auto s2 = std::make_shared<std::stack<int>>();
    auto s2_copy(s2); // can be copied
    s2->push(4);

    // Dynamically allocated, gets auto-deleted when the
    // smartpointer goes out of scope. No overhead, but
    // cannot be copied / shared.
    // Works out-of-the-box with arrays as well.
    auto s3 = std::make_unique<std::stack<int>>();
    s3->push(4);
}

Answer 3

您必须创建对象然后才能指向它。

#include<iostream>
#include<stack>

using namespace std;

int main() {
    stack<int> s;
    stack<int>& S = s;
    S.push(4);
    return 0;
}